Automatic telephone system



1940- M. LANGER ET AL AUTOMATIC TELEPHONE SYSTEM Filed April 25, 1958 Patented' JanQ 16, 1940 PATENT OFFICE AUTOMATIC TELEPHONE SYSTEM Max Langer, Berlin-Heemsdorf, and Georg Zapf, Berlin-Charlottenburg, Germany, assignors t Siemens & Halske Aktiengesellschaft, Wernerwerk, Siemensstadt, near Berlin, Germany Application April 25, 1938, Serial No. 204,004

' In Germany May 10, 1937 6 Claims.

The problem of the present invention is to enable differential ringing in systems in which the different kindsof calls pass over the same final.

selector which is equipped with automatic ringing devices, and the problem is solved in that the ringing devices arranged in the final selector transmit ringing current periodically after the subscribers line has tested free independently of the type of call and switching means are associated with the connecting paths for calls of different types which superimpose on the. periodic ringing current of the. final selector ringing current-of different duration and/or with different intervals l The arrangement according to the invention hasthe special advantage that no disconnecting devices are required for the automatic ringing in the final selector.

In the drawing an embodiment of the invention for telephone systems with local and long distance working is represented. All the switching devices and circuits which are not absolutely necessary for the understanding of the invention have been omitted for the sake of clarity. In the top left-hand corner of the drawing is represented a subscriber's station N for local calls which reach a final selector LW which is provided both for local and distant calls over a call finder AS and a groupselector GW and over which the desired local call can be established. Distant calls can be established from the trunk position. FPL in the left-hand bottom corner over a repeater F 5 and a group selector FGW to the same final selector LW and over this to the desired local subscriber. v i

The establishment of a local call will first be described briefly:

When the subscriber at station .N takes up his receiver the call finder AS is started up in the known way and connects the calling subscribers line to airee group selector GW. Relays R and C energize over the lower wiper of the call finder and over the :ofi normal contact lk of the group selector. Relay R switches through the subscribers line to the line relay A over contacts 21" r and 37 and this relay also energizes. For the purpose ofsetting the group selector on a free final selector in the desired group the subscriber transmits an impulse train whereby relay A is deenergized impulsively. On each impulse the following circuit is set up for the vertical magnet of the group selector: earth, contacts 4a and 5c, rotary off-normal contact two of the group selector, winding I'of relay V,winding of the vertical magnet H, battery and earth. As soon as the vertical magnet has taken the first vertical step contact We is opened. Relays R. and C then hold up over contact To, which has meanwhile closed.

At the end of the impulse train transmitted by the subscriber relay V releases, so that the rotary magnet D is energized over the off-normal contact 8k also closed on the first Vertical step of the vertical magnet and over contacts 911 and Hip and over the interrupter Un and moves the wipers of the group selector on one step. The circuit for the rotary magnet D is broken periodically by the interrupter Un until the test relay P is energized over the following circuit when the low er wiper of the group selector tests on a free final selector: earth, contacts i la and l2a, windings I and II of relay P, lower wiper of GW, off-normal contact i320 of the final selector LW, the winding of relay C'I, battery and earth, Relay P shortcircuits its high resistance winding 11' at con- 1,

tact lip and thus guards the seized, final selector in the known way. The speaking leads of the group selector are switched through to the final selector at contacts ifip and I67).

If now a further impulse train is transmitted from the calling station N for setting the final selector relay A falls back again on each impulse and completes a circuit for windings I and II of relay Al in the final selector LW over contacts llc, lfia and 15p and the upper wiper of the group selector GW. Each time this relay energizes it sets up a circuit for the vertical magnet Hl of the final selector by closing its contact 'l al, over winding I of relay VI, and contacts Zllu and 2 lw. Relay Vl remains energized throughout the impulse train since on account of its winding II being short-circuited periodically at contact 22a! it operates as a slow relay. On the first vertical step contact l3k in the test circuit is opened. The test relay P in the group selector and relay Cl in the final selector hold up over contact 230i. When the first impulse train operating on the final selector LW has terminated relay V! releases and closes the following circuit for relay U: off-normal contact 2470, contacts 250i and 260i, winding I of relay U, contact 2Iw, the winding of the vertical magnet HI, battery and earth. In this circuit only relay U energizes while the vertical magnet HI on account of the high resistance of this relay does not receive sufficient current to energize. Relay U closes its contact Z'Iu and thus switches over the circuit controlled by contact Ital on to the rotary magnet of thefinal selector over contact 28m. This magnet is energized by the next impulse train sent out by the subscriber N and sets the wipers of the final selector LW on the contacts of the wanted line. It should be mentioned that relay U remains energized over a second winding II over contacts 2912i, 3614 and 3IcI during the infiuencng of the rotary magnet. When now relay VI releases at the end of the impulse train contact 29115 is. opened and this promotes the release of relay U. During the release period of this relay, relay PI can operate over contacts 3Ici, Stu and 32m if the wanted line is free. It switches the speaking leads through at contacts 33pl and MM and by closing its contact 3512i energizes winding III of relay VI over contacts 36y and 31a so long as relay U has not released. Ringing current from the ringing machine RM is transmitted to the subscribers line as the socailed first ringing pulse over contact 33p! and the upper wiper of the first selector. When relay U releases, relay VI energized temporarily over contact 3914 and the Ill-seconds switch ZS every 10 seconds and thus applies ringing current to the subscribers line periodically over the above-mentioned path. When the called subscriber replies relay Y energizes and breaks the ringing circuit by opening contact 36y.

When the call is terminated relay A releases in the group selector when the party at station N replaces his receiver and short-circuits the windings of relay C at contact 48a. The circuit for relay P in the group selector and for relay CI in the final selector is broken at contact lie. The said selectors are thus restored to normal.

The establishment of a trunk call by the operator at the trunk position FPL will now be described. For setting up such a call the operator inserts the plug St in the jack Kl of a free trunk repeater FU thereby energizing relay C2 of this repeater. It closes itscontacts 4Ic2, 42c2 and 4302, switches the speaking leads through to the trunk group selector FGW at the latter contacts and over the first contact and the offnormal contact Mk of the group selector FGW energizes the seizing relay C3. trunk group selector the operator now operates her dial switch of which the contacts y and 728 are shown. Contact us is operated when the dial is pulled off-normal and remains closed until the end of its run back. Relay B in the repeater FIT is thereby energized and by closing its contact 451) switches the upper speaking lead coming from the trunk jack through to the impulse receiving relay A3 in the group selector FGW. At each impulse contact 3 of the dial switch is closed and energizes relay All which sets the group selector in the known way. When it tests on a free succeeding final selector, for example the selector LW shown in the drawing relay P2 energizes over the lower wiper of FGW and contact I375 and the winding of relay CI. The test relay P2 closes its contacts fifipt and 11732 whereby the speaking leads coming from the repeater FU are switched through to the seized final selector over the wipers of EGW. The setting of the final For setting the selector takes place in the same way as described above. When the selector LW is seized however the following circuit is set up for relay G in the repeater earth, winding of relay Y in the final selector, resistance Wil, contact 4am, lower speaking lead of LW, middle wiper of FGW, contacts 4'Ip2, 4202 and 19b, winding I of relay G, battery and earth. RelayG energizes and locks up over its winding II over contacts 5002 and Ig while relay Y in the final selector on account of thehigh resistance of relay G does not receive sufficient current to energize. On the first impulse train for setting the final selector relay B in the repeater FU energizes again'and closes the following circuit: earth, contacts 5002, 52 and 53b, resistance WM, winding I of relay GI, battery and earth. Relay GI is a two-stage relay and only energizes partially over the resistance Wi4 whereupon its contacts 54911 and 55gII are closed. At the end of the impulse train relay B releases and completes a circuit for winding II of relay GI over contacts 5002, 52y, 56b and MgII. Over this winding relay GI energizes completely and closes its contacts 5'IgIII and 58gIII. When the second impulse train for setting the final selector is transmitted relay B is energized in the repeater Fill and completes the following circuit for relay G2: earth, contacts 5002, 5%

and SBgIII, the winding of relay G2, battery and earth. By closing its contact 6Bg2 relay G2 locks up and at contact 6892 prepares the circuit for the ring connecting relay F; At the end of the said impulse train relay B releases so that the following circuit is closed periodically for relay F: battery, the winding of relay F, contacts 62b, 6Ig2, 63s, ISaZ, the five seconds switch FS and. earth. The switch FS closes the above circuit every five seconds so that the ringing machine RM is connected to the upper speaking lead over contact 64 periodically. In this way a five-seconds ringing is superimposed by the repeater F6 on the ten seconds ringing being transmitted 'from the final selector when this tests free so that the called subscriber can determine from this particular kind of ringing that he is wanted for a trunk call. Naturally the ringing current superimposed on the automatic ringing from. the final selector can be applied in difierent intervals or it may possess a different duration from the first mentioned ringing, for example it may be longer.

When the wanted party replies the following feeding circuit is established for him: earth, the Winding of relay Y, contact 34pl, the middle- Wiper of LW, the subscribers loop, the upper wiper of LW, contacts 33pl, IIivI, winding II of relay AI, battery and earth. In parallel with winding II of relay AI relay S is energized over the winding I of relay AI, the upper wiper of FGW and contacts 46122, 4302, $51) and 66) and this relay by opening its contact 535 breaks the circuit for the ring connecting relay F in the repeater PU and thus disconnects the periodic ringing. The disconnection of the ringing in the final selector takes place at contact 36y as indicated in the above description of a local call.

If the subscriber wanted for the trunk call should be busy a busy signal applied in the final selector LW in the known way is transmitted to the operator at the trunk position FPL over contact 66] in the repeater FI'T during the ringing pauses. In this case the ringing current applied at contact 64f cannot reach the subscribers sta- "I tlon since the contacts 331)!" and 3417! in the final selector are open. The operator thereupon operates her busy connecting key AT and thus connects battery to both speaking leads of the cord circuit. .Consequently relay'B in the repeater FU and relay A2 (Winding I) are energized over the contact .6'lg2. By opening its contact 19122, relay AZ breaks the circuit for the ring connecting relay F and locks up over its winding II over contacts Hat; through the closing of COD.

tact 68b and 69a2, battery is applied to the lower speaking lead over the low resistance Wi3 in the repeater Ff? and thus relay Y in the final selector is energized over contacts 4202, 41102 and 48a! and the-resistance Wil. Relay Y closes contact 101/ and Hy at which the speaking leads are switched through to the seized subscribers line over condensers. The'operator can now inform the subscriber who is engaged in a localcall of the presenceof the trunk call and can cut ofi the trunk call by switching over cut-off key TT. By this means on the one hand relay B is operated again which released when the busy connecting key AT was released and on the other hand by applying earth to the left-hand lead of the cord circuit over the contacts 45?), 4302 and 46 02 en- This causes relay PI to be short-circuited in the,

final selector which holds the wanted subscribers linefbusy in the known way. If meanwhile the wanted subscriber has replaced his receiver he can be rung again by the operator by the latter switching over her ringing key RT. The trunk I call is released by the withdrawal of the plug St from the jack Kl at the trunk position on hearing the clearing signal.

What is claimed is: I

1. In a telephone system, a substation, signal receiving means at the substation actuable when the substation is not engaged in a call, a plurality of signal transmitters, means forextending calls to said substation, means for rendering one of said transmitters effective alone in certain of said 1 calls, and means for rendering more than one of said transmitters effective concurrently in others of said calls, thereby to actuate said first means difierently in difierent calls. 1

2. In a telephone system, two sources of signalling current, a substation, means for extending a connection to said substation and for transmitting thereto signalling current from one source alone, or, alternatively, from both sources concurrently, and means at the substation actuated distinctively by said signalling current in dependence upon whether same is from one or both sources.

'3. In a telephone system, means for generating codes differing in character, a substation, means for extending a connection to said substation and for transmitting over said connection one of said codes alone, or, alternatively, a plurality of said codes concurrently, and responding means at the substation actuated distinctively in dependence upon whether said one code or said plurality of codes are transmitted over the connection.

l. In a telephone system, a substation, signal receiving means at said substation actuable when the substation is not engaged in a call, means for extending calls of different values to said substation, a plurality of signal transmitters, means for rendering one of said transmitters effective alone if a call of one value is extended to said substation, and means for rendering more than one of said transmitters effective concurrently if a call of another value is extended to said substation, thereby to actuate said first means differently depending upon the value of the call extended to said substation.

5. In a telephone system, a plurality of signal transmitters, a substation,.means for extending calls of different values to said substation, means operated when a call is extended to said substation to render one of said transmitters effective regardless of the value of said call, means operated only if the call is of a particular value to render another of said transmitters effective, and responding means at said substation controlled at times by said first transmitter alone and controlled concurrently bysaid two transmitters only if said call is of said particular value.

6. In a telephone system, subscriber lines, an operators position, an automatic switch, means 'for extending a connection from a calling one of the lines or from said position to said automatic switch and for controlling said switch to extend said connection to any desired one of said lines, means in said switch for thereupon transmitting signalling current over said desired line, means associated with said position effective if said connection is extended therefrom to also transmit MAX LAN GER. GEORG ZAPF. 

